Cottonseed oil color reversion prevention



United States Patent COTTONSEED on. COLOR REVERSION PREVENTION No Drawing. Application August 12, 1953,

Serial No. 373,927

3 Claims. (Cl. 260-424) (Granted under Title 35, U. S. Code (1952), see. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, for all governmental pur-,

poses, throughout the world, with the power to grant sublicenses for such purposes, is hereby grantedto the Government of the United States of America.

This invention relates to the processing and storage of crude cottonseed oil and provides a method of preventing losses in oil quality during storage.

Cottonseed contains a number of highly colored pigments such as gossypol and related materials and the carotenoids and related materials. In the newer methods of extracting oil from cottonseed, in which essentially all of the oil is removed from the seed, the crude cottonseed oil contains appreciable amounts of these highly colored pigments.

When freshly extracted crude cottonseed oil is refined by an alkali refining process the gossypol and related materials are removed along with free fatty acids and other acidic components by the action of the alkali; and the carotenoids and related colored materials then removed by the action of an adsorbent bleaching material. However, because of the distances between many of the oil mills and the refining plants, it is often necessary to store crude cottonseed oils for several months prior to refining. During the storage, pigments such as gossypol and related materials often undergo chemical changes of such a nature that they can no longer be removed from the stored oils with alkali. This phenomenon is known as "color reversion. When an oil has undergone color reversion, the ordinary refining and bleaching procedures fail to remove the colored, chemically changed gossypol resulting in the production of low grade oils which sell at a lower price and to a more limited market than those commanded by the higher grade oils.

An object of this invention is to provide a simple and efiicient method of preventing color reversion. A further object is to provide a method of treating cottonseed oil which has undergone color reversion, to improve the refining and bleaching characteristics of the oil.

In general, the process of this invention comprises mixing and reacting crude cottonseed oil containing gossypol and related pigments with a minor amount, at least stoichiometrically equivalent to the amount of the gossycottonseed oil with alkali.

2,787,625 Patented Apt. 2, 1957 pol and related pigments, of a non-toxic, acid group containing compound, which is capable of being removed from cottonseed oil by alkali refining, and which is capable of reactingwith gossypol and related pigments at from about 20 to 80 C. to form solid, cottonseed oil insoluble, acid group containing derivatives which are capable of being removed from cottonseed oil both by mechanical means and by alkali refining, and removing substantially all of the derivatives produced by the reaction of said compound with gossypol and related materials by mechanical means prior to refining the so treated crude The compounds with which crude cottonseed oil is mixed in accordance with this invention are hereinafter referred to by the term acid group-containing gossypol reactants.

Para-aminobenzoic acid is a particularly suitable acid group-containing gossypol reactant.

The acid group containing gossypol reactants can be mixed with crude cottonseed oil in the form of individual or mixed solids or liquids, or in the form of solutions of such compounds in inert cottonseed oil miscible solvents.

The mixing can be conducted at from a temperature at which the cottonseed oil becomes too viscous to be readily agitated to a temperature at which the thermal decomposition of the cottonseed oil becomes appreciable. The mixing is preferably conducted at temperatures from about 20 C. to about 80 C.

The solid, cottonseed oil insoluble, acid group-containing derivatives resulting from the mixing of the acid group-containing gossypol reactants with crude cotton-.

seed oil can be removed by mechanical means such as settling and decantation, filtration, or centrifugation prior to refining the oil in which they were produced with alkali. The removal of these derivatives can precede or follow the storage of the mixture of cottonseed oil and the acid group-containing gossypol reactant.

The amount of acid group-containing gossypol reactant to be mixed with the crude cottonseed oil can be determined by making a conventional determination of the gossypol content of the oil and calculating the amount needed to provide a slight excess on the basis of 2 moles of a monofunctional amino compound reacting with 1 mole of gossypol or by simply adding increments of the acid group-containing gossypol reactant until further additions do not produce further reaction. The use of an amount just slightly greater than the stoichiometrically equivalent amount is generally preferred.

The following examples are illustrative of details of the preferred embodiment of this invention using paraaminobenzoic acid.

In the examples shown in Table l, the indicated types of commercially extracted cottonseed oils were mixed with para-aminobenzoic acid, stored and freed of colored materials, as indicated. In each case slightly more than 2 moles of para-aminobenzoic acid per mole of gossypol, on the basis of the gossypol content, were mixed with the oil at a temperatureof from about C. to C.

7 able 1.-T he effect ofthe prior addition o/paminobcnzoic acid onthe refin lina and'blzaching properties of crude cottonseed oils ajter storage at 100 F. for thirty aux Data on samples before storage are enclosed in parentheses Cottonseed 011 Treatment Gossypol, Refining Refined Bleached percent Loss, percent Color Color Control (0.82) 70 (6. 9) 7.2 (S. 3) 19.3 (2.9) 13.0 Solvent Extracted {Control PABA 1 (9. 7) 10.8 (9. 6) 13. (4.1) 6.3 Control PABA; filtered. 10.8 6.1 1.3 Control (0. 65) (10. 2) 10. 7 (7. 2) 0. 1 (2. 8) 4. 3 Screw-pressed (Anderson Expeller) {Cont l (9.7) 9.5 (8.6) 7.0 (2.6) 2.2 80mm! storcd, l 1 "Egg; .7565. smw'pressed (French Type) icg iiiof-Fr X13 I (s: s 01 2 (51 1) 41g (11g) 11 5 r 5.4 6.6 5.1 5. l. 1. 6 screw'm'essed (Pwplessed) i2. 83 1. 9 i4. si 4. 4 1. ii 1.0 (10. 3) 10. 6 (7. 4) l0. 5 2. 8) 5.1 Screw-pressed (5.0) 6. 5 (6. 6) 5. 1 2. 1) 1. 9 7.7 8. 5 3.5 C 01 (8. 0) 7. 5 (0.1) 7. 6 (1. 9) 3.0 Hydraulic-pressed Coutrol PABA; filtered 0.00 (4. 9) 5.2 (5.4) 4. 5 (L7) 1.4 Coutrol;stored;+ P .'\BA;filtcred 0.00 7.7 6.3 2.3

We claim: mechanical means prior to refining the so treated oil with 1. A process comprising mixing and reacting crude cottonseed oil containing gossypol and related pigments with a minor amount, at least stoichiometrically equivalent to the amount of the gossypol and the related pigments, of para-aminobenzoic acid, and removing substantially all of the solid, cottonseed oil insoluble derivatives, produced by the reaction of said para-aminobcnzoic acid with the gossypol and the related materials, by mechanical means prior to refining the so treated crude cottonseed oil with alkali.

2. A process of preventing the color reversion of a crude cottonseed oil containing gossypol and related pigments comprising mixing and reacting freshly extracted crud-z cottonseed oil containing gossypol and related pigments with a minor amount, at least stoichiomctrically equivalent to the amount of the gossypol and the related materials, of para-aminobcnzoic acid, and removing substantially all of the solid, cottonseed oil insoluble derivatives, produced by the reaction of said para-aminobcnzoic acid with the gossypol and the related materials, by

alkali.

3. A process of improving the refining and bleaching properties of crude cottonseed oil containing gossypol and related pigments and which has undergone color reversion comprising, mixing and reacting said oil with a minor amount, at least stoichiomctrically equivalent to the amount of the gossypol and the related materials, of para-aminobenzoic acid, and removing substantially all of the solid, cottonseed oil insoluble derivatives, produced by the reaction of said para-aminobcnzoic acid with the gossypol and the related materials, by mechanical means prior to refining the so treated oil with alkali.

Rcfercuces Cited in the file of this patent UNITED STATES PATENTS 2,164,012 Hund et al. June 27, 1939 2,638,476 James May 12, 1953 OTHER REFERENCES Bailey: Cottonseed, 1948, page 331. 

1. A PROCESS COMPRISING MIXING AND REACTING CRUDE COTTONSEED OIL CONTAINING GOSSYPOL AND RELATED PIGMENTS WITH A MINOR AMOUNT, AT LEAST STOICHIOMETRICALLY EQUIVALENT TO THE AMOUNT OF THE GOSSYPOL AND THE RELATED PIGMENTS, OF PARA-AMIOBENZOIC ACID, AND REMOVING SUBSTANTIALLY ALL OF THE SOLID, COTTONSEED OIL INSOLUBE DERIVATIVES, PRODUCED BY THE REACTION OF SAID PARA-AMINOBENZOIC ACID WITH THE GOSSYPOL AND THE RELATED MATERIALS, BY MECHANICAL MEANS PRIOR TO REFINING THE SO TREATED CRUDE COTTONSEED OIL WITH ALKALI. 